Abstract: Provided herein are polypeptides and polynucleotides encoding such polypeptides which have ketoisovalerate decarboxylase activity. Also provided are recombinant host cells comprising such polypeptides and polynucleotides and methods of use thereof.

Abstract: A high flux of metabolites from pyruvate to 2,3-butanediol in Lactobacillus plantarum was achieved through genetic engineering. Substantial elimination of lactate dehydrogenase activity in the presence of heterologously expressed butanediol dehydrogenase activity led to 2,3 butanediol production that was at least 49% of the total of major pyruvate-derived products.

Abstract: The present invention is related to a recombinant host cell, in particular a yeast cell, comprising a dihydroxy-acid dehydratase polypeptide. The invention is also related to a recombinant host cell having increased specific activity of the dihydroxy-acid dehydratase polypeptide as a result of increased expression of the polypeptide, modulation of the Fe—S cluster biosynthesis of the cell, or a combination thereof. The present invention also includes methods of using the host cells, as well as, methods for identifying polypeptides that increase the flux in an Fe—S cluster biosynthesis pathway in a host cell.

Abstract: Ketol-acid reductoisomerase enzymes have been identified that provide high effectiveness in vivo as a step in an isobutanol biosynthetic pathway in bacteria and in yeast. These KARIs are members of a clade identified through molecular phylogenetic analysis called the SLSL Clade.

Abstract: Bacteria that are not natural butanol producers were found to have increased tolerance to butanol when the saturated fatty acids content in bacterial cell membrane was increased. Methods for increasing the concentration of saturated fatty acids in the membranes of bacteria that are not natural butanol produces are described whereby tolerance of the bacterial cell to butanol is increased. Saturated fatty acids concentration in the bacterial cell membrane increased upon exogenously feeding saturated fatty acids to cells. Bacterial strains useful for production of butanol are described herein having modified unsaturated fatty acid biosynthetic pathway.

Abstract: An engineering method was developed to allow genetic modification and isolation of lactic acid bacteria cells that lack lactate dehydrogenase and acetolactate decarboxylase activities. In cells with these modifications and an isobutanol biosynthetic pathway, improved production of isobutanol was observed.

Abstract: A microbial host cell is provided for the production of isobutanol. Carbon flux in the cell is optimized through the Entner-Doudoroff pathway.

Abstract: A high flux of metabolites from pyruvate to 2,3-butanediol in Lactobacillus plantarum was achieved through genetic engineering. Substantial elimination of lactate dehydrogenase activity in the presence of heterologously expressed butanediol dehydrogenase activity led to 2,3 butanediol production that was at least 49% of the total of major pyruvate-derived products.

Abstract: Lactic acid bacteria expressing dihydroxyacid dehydratase polypeptides with increased specific activity are disclosed. The lactic acid bacteria comprise recombinant genes encoding iron-sulfur cluster forming proteins.

Abstract: Lactic acid bacterial (LAB) cells were modified such that they have a specific activity of dihydroxy-acid dehydratase enzyme activity that is increased to about 0.1 ?mol min?1 mg?1. LAB cells with even higher activities of 0.2 to 0.6 ?mol min?1 mg?1 of DHAD activity were obtained. These modified cells may be used to produce isobutanol when additional isobutanol biosynthetic pathway enzymes are expressed.